A SPECIAL REPORT SERIES BY THE N.C. DEPARTMENT OF HUMAN RESOURCES, DIVISION OF
HEALTH SERVICES, STATE CENTER FOR HEALTH STATISTICS, P.O. BOX 2091, RALEIGH, N.C. 27602
N0-33 North Carolina State Library J December 1984
RaleiRh
THE GEOGRAPHIC PATTERN OF TUBERCULOSIS IN NORTH CAROLINA
by
Michael J. Patetta
I. INTRODUCTION
In 1918, there were 3,514 cases of tuberculosis
(ТВ)
in
North Carolina, which is a case rate of 139.34 per 100,000
population (1). There were also 3,412 deaths from
ТВ
for
a death rate of 135.30 (2). The case rate of
ТВ
has gone
down considerably, however, as in 1982 it was 13.5 per
100,000 population (3). Furthermore, only 63 people died
from
ТВ
in 1982 for a death rate of 1.05 per 100,000
population (4). Despite the decline in the number of
cases,
ТВ
is still a serious public health problem in North
Carolina. The state’s case rate ranked 12th highest in the
U.S. in 1982 (5). What is even more perplexing, however,
is the preponderance of
ТВ
in eastern North Carolina.
The map in Figure 1 clearly shows this strong geographic
pattern of county morbidity rates for
ТВ.
The major objectives of this paper are:
1) to summarize the current morbidity and health care
delivery data on
ТВ
in North Carolina;
2) to provide indicators why an eastern band of coun¬
ties has more than triple the
ТВ
morbidity rate of the
rest of the state;
3) to see if the counties with high
ТВ
rates have high
rates throughout the county or just in certain parts of
the county;
4) to expand the study area and see if Virginia and
South Carolina also have this eastern band of coun¬
ties with a high incidence of
ТВ.
II. BACKGROUND
The primary cause of
ТВ
is a bacterium called the
tubercle bacillus (mycobacterium tuberculosis).
Infection occurs through the inhalation of the organisms
present in the air or droplet nuclei expelled by the
coughing or sneezing of a person with active
ТВ.
The
measurable manifestation of infection is a positive
tuberculin skin test; however, signs and symptomsof
ТВ
may be absent. Once infected, the person's immune
system usually proves adequate to limit the multiplica¬
tion and spread of the bacilli. Around 5% of newly
infected individuals, though, do develop
ТВ
disease
within a year of their infection (6). If the bacilli produces
ТВ
in the lung, then the disease is called pulmona'ry
ТВ,
All other sites of
ТВ
are called extra-pulmonary
ТВ.
Vague general symptoms such as fatigue, nervous
irritability, or anorexia usually signal the onset of pulmo¬
nary
ТВ
(7). Later symptoms include a cough, a cold,
blood spitting, unexplained fever and night sweats, loss
of weight and swollen glands (8). The symptoms for
extra-pulmonary
ТВ
depend upon where the
ТВ
develops.
Approximately 85% of the reported cases of
ТВ
in the
U.S. are pulmonary
ТВ
(9). It is much more a public
health problem than extra-pulmonary
ТВ
since it usually
is more contagious. In pulmonary T8, a cavity is fre¬
quently formed in the lung and large numbers of viru¬
lent bacilli are released from this cavity daily. Pulmonary
ТВ,
however, is not a highly infectious disease when
compared to other diseases since transmission usually
requires close, frequent, or prolonged exposure (10).
Among persons infected with the tubercle bacillus,
only about 5-10% ever develop
ТВ
disease (11). However,
because the organisms remain viable within the body for
decades, the risk of disease is lifelong. The precise factors
that determine whether any infected individual will
